4,605 research outputs found
Aerobee 350, flight 17.03 GE - Instrumentation information and calibration data
Airborne instrumentation system on Aerobee 350 sounding rocke
Fermionic Zero Modes on Domain Walls
We study fermionic zero modes in the domain wall background. The fermions
have Dirac and left- and right-handed Majorana mass terms. The source of the
Dirac mass term is the coupling to a scalar field . The source of the
Majorana mass terms could also be the coupling to a scalar field or a
vacuum expectation value of some other field acquired in a phase transition
well above the phase transition of the field . We derive the fermionic
equations of motion and find the necessary and sufficient conditions for a zero
mode to exist. We also find the solutions numerically. In the absence of the
Majorana mass terms, the equations are solvable analytically. In the case of
massless fermions a zero energy solution exists and we show that although this
mode is not discretely normalizable it is Dirac delta function normalizable and
should be viewed as part of a continuum spectrum rather than as an isolated
zero mode.Comment: 6 pages, 3 figures, matches version published in PR
The Physical Conditions in Starbursts Derived from Bayesian Fitting of Mid-IR SEDS: 30 Doradus as a Template
To understand and interpret the observed Spectral Energy Distributions (SEDs)
of starbursts, theoretical or semi-empirical SED models are necessary. Yet,
while they are well-founded in theory, independent verification and calibration
of these models, including the exploration of possible degeneracies between
their parameters, are rarely made. As a consequence, a robust fitting method
that leads to unique and reproducible results has been lacking. Here we
introduce a novel approach based on Bayesian analysis to fit the Spitzer-IRS
spectra of starbursts using the SED models proposed by Groves et al. (2008). We
demonstrate its capabilities and verify the agreement between the derived best
fit parameters and actual physical conditions by modelling the nearby,
well-studied, giant HII region 30 Dor in the LMC. The derived physical
parameters, such as cluster mass, cluster age, ISM pressure and covering
fraction of photodissociation regions, are representative of the 30 Dor region.
The inclusion of the emission lines in the modelling is crucial to break
degeneracies. We investigate the limitations and uncertainties by modelling
sub-regions, which are dominated by single components, within 30 Dor. A
remarkable result for 30 Doradus in particular is a considerable contribution
to its mid-infrared spectrum from hot ({\simeq} 300K) dust. The demonstrated
success of our approach will allow us to derive the physical conditions in more
distant, spatially unresolved starbursts.Comment: 17 pages, 10 figures. Accepted por publication in the Astrophysical
Journa
SN1991bg-like supernovae are associated with old stellar populations
SN1991bg-like supernovae are a distinct subclass of thermonuclear supernovae
(SNe Ia). Their spectral and photometric peculiarities indicate their
progenitors and explosion mechanism differ from `normal' SNe Ia. One method of
determining information about supernova progenitors we cannot directly observe
is to observe the stellar population adjacent to the apparent supernova
explosion site to infer the distribution of stellar population ages and
metallicities. We obtain integral field observations and analyse the spectra
extracted from regions of projected radius about the
apparent SN explosion site for 11 91bg-like SNe in both early- and late-type
galaxies. We utilize full-spectrum spectral fitting to determine the ages and
metallicities of the stellar population within the aperture. We find that the
majority of the stellar populations that hosted 91bg-like supernovae have
little recent star formation. The ages of the stellar populations suggest that
that 91bg-like SN progenitors explode after delay times of ,
much longer than the typical delay time of normal SNe Ia, which peaks at .Comment: 12 pages, 3 figures, 3 tables, submitted to Publications of the
Astronomical Society of Australi
Depletion of polycistronic transcripts using short interfering RNAs: cDNA synthesis method affects levels of non-targeted genes determined by quantitative PCR.
BACKGROUND: Short interfering RNAs (siRNAs) are often used to deplete viral polycistronic transcripts, such as those encoded by human papillomavirus (HPV). There are conflicting data in the literature concerning how siRNAs targeting one HPV gene can affect levels of other genes in the polycistronic transcripts. We hypothesised that the conflict might be partly explained by the method of cDNA synthesis used prior to transcript quantification. FINDINGS: We treated HPV16-positive cervical keratinocytes with siRNAs targeting the HPV16 E7 gene and used quantitative PCR to compare transcript levels of E7 with those of E6 and E2, viral genes located upstream and downstream of the target site respectively. We compared our findings from cDNA generated using oligo-dT primers alone with those from cDNA generated using a combination of random hexamer and oligo-dT primers. Our data show that when polycistronic transcripts are targeted by siRNAs, there is a period when untranslatable cleaved mRNA upstream of the siRNA binding site remains detectable by PCR, if cDNA is generated using random hexamer primers. Such false indications of mRNA abundance are avoided using oligo-dT primers. The period corresponds to the time taken for siRNA activity and degradation of the cleaved transcripts. Genes downstream of the siRNA binding site are detectable during this interval, regardless of how the cDNA is generated. CONCLUSIONS: These data emphasise the importance of the cDNA synthesis method used when measuring transcript abundance following siRNA depletion of polycistronic transcripts. They provide a partial explanation for erroneous reports suggesting that siRNAs targeting HPV E7 can have gene-specific effects.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
A nuclear localization signal targets tail-anchored membrane proteins to the inner nuclear envelope in plants
Protein targeting to the inner nuclear membrane (INM) is one of the least understood protein targeting pathways. INM proteins are important for chromatin organization, nuclear morphology and movement, and meiosis, and have been implicated in human diseases. In opisthokonts, one mechanism for INM targeting is transport factor-mediated trafficking, in which nuclear localization signals (NLSs) function in nuclear import of transmembrane proteins. To explore whether this pathway exists in plants, we fused the SV40 NLS to a plant ER tail-anchored protein and showed that the GFP-tagged fusion protein was significantly enriched at the nuclear envelope (NE) of leaf epidermal cells. Airyscan subdiffraction limited confocal microscopy showed that this protein displays a localization consistent with an INM protein. Nine different monopartite and bipartite NLSs from plants and opisthokonts, fused to a chimeric tail-anchored membrane protein, were all sufficient for NE enrichment, and both monopartite and bipartite NLSs were sufficient for trafficking to the INM. Tolerance for different linker lengths and protein conformations suggests that INM trafficking rules might differ from those in opisthokonts. The INM proteins developed here can be used to target new functionalities to the plant nuclear periphery
Sequential pivotal mechanisms for public project problems
It is well-known that for several natural decision problems no budget
balanced Groves mechanisms exist. This has motivated recent research on
designing variants of feasible Groves mechanisms (termed as `redistribution of
VCG (Vickrey-Clarke-Groves) payments') that generate reduced deficit. With this
in mind, we study sequential mechanisms and consider optimal strategies that
could reduce the deficit resulting under the simultaneous mechanism. We show
that such strategies exist for the sequential pivotal mechanism of the
well-known public project problem. We also exhibit an optimal strategy with the
property that a maximal social welfare is generated when each player follows
it. Finally, we show that these strategies can be achieved by an implementation
in Nash equilibrium.Comment: 19 pages. The version without the appendix will appear in the Proc.
2nd International Symposium on Algorithmic Game Theory, 200
Heating and cooling of the neutral ISM in the NGC4736 circumnuclear ring
The manner in which gas accretes and orbits within circumnuclear rings has
direct implications for the star formation process. In particular, gas may be
compressed and shocked at the inflow points, resulting in bursts of star
formation at these locations. Afterwards the gas and young stars move together
through the ring. In addition, star formation may occur throughout the ring, if
and when the gas reaches sufficient density to collapse under gravity. These
two scenarios for star formation in rings are often referred to as the `pearls
on a string' and `popcorn' paradigms. In this paper, we use new Herschel PACS
observations, obtained as part of the KINGFISH Open Time Key Program, along
with archival Spitzer and ground-based observations from the SINGS Legacy
project, to investigate the heating and cooling of the interstellar medium in
the nearby star-forming ring galaxy, NGC4736. By comparing spatially resolved
estimates of the stellar FUV flux available for heating, with the gas and dust
cooling derived from the FIR continuum and line emission, we show that while
star formation is indeed dominant at the inflow points in NGC 4736, additional
star formation is needed to balance the gas heating and cooling throughout the
ring. This additional component most likely arises from the general increase in
gas density in the ring over its lifetime. Our data provide strong evidence,
therefore, for a combination of the two paradigms for star formation in the
ring in NGC4736.Comment: accepted for publication in A&
Supporting home care for the dying: an evaluation of healthcare professionals' perspectives of an individually tailored hospice at home service
AIMS AND OBJECTIVES: To explore health care professionals' perspective of hospice at home service that has different components, individually tailored to meet the needs of patients. BACKGROUND: Over 50% of adults diagnosed with a terminal illness and the majority of people who have cancer, prefer to be cared for and to die in their own home. Despite this, most deaths occur in hospital. Increasing the options available for patients, including their place of care and death is central to current UK policy initiatives. Hospice at home services aim to support patients to remain at home, yet there are wide variations in the design of services and delivery. A hospice at home service was developed to provide various components (accompanied transfer home, crisis intervention and hospice aides) that could be tailored to meet the individual needs of patients. DESIGN: An evaluation study. METHODS: Data were collected from 75 health care professionals. District nurses participated in one focus group (13) and 31 completed an electronic survey. Palliative care specialist nurses participated in a focus group (9). One hospital discharge co-ordinator and two general practitioners participated in semi-structured interviews and a further 19 general practitioners completed the electronic survey. RESULTS: Health care professionals reported the impact and value of each of the components of the service, as helping to support patients to remain at home, by individually tailoring care. They also positively reported that support for family carers appeared to enable them to continue coping, rapid access to the service was suggested to contribute to faster hospital discharges and the crisis intervention service was identified as helping patients remain in their own home, where they wanted to be. CONCLUSIONS: Health care professionals perceived that the additional individualised support provided by this service contributed to enabling patients to continue be cared for and to die at home in their place of choice. RELEVANCE TO CLINICAL PRACTICE: This service offers various components of a hospice at home service, enabling a tailor made package to meet individual and local area needs. Developing an individually tailored package of care appears to be able to meet specific needs
Reversible Photoreduction as a Trigger for Photoresponsive Gels
We present here a new type of photoresponsive, reversible low molecular weight gel. All previous examples rely on a photoisomerisation, ring-closing or dimerization. We show that photoreduction of a perylene bisimide gelator results in the formation of a stable radical anion. The formation of the radical anion results in a change in the packing of the perylene bisimides in the self-assembled aggregates, leading to a change in fibrous network and an increase in the rheological properties of the gels. An increase in the rheological properties is extremely rare for a photoresponsive gel; normally, irradiation results in a gel-to-sol transition, and the gel falling apart. As the radical anion decays, which takes several hours in air, the original gel properties are restored. This photoreduction can be cycled many times. Finally, we show that the mechanical properties are different between irradiated and nonirradiated sections in a patterned gel
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